Answer:
a. 2,727
b. (85.6%, 87.6%)
Step-by-step explanation:
The percentage of the adults aged 57 through 85 that used at least one prescription medication = 86.6%
a. The expected number of the 3,149 subjects aged 57 through 85 that used at least one prescription medication = 3,149 × 86.6/100 = 2,727.034 ≈ 2,727 (subjects)
b. The 90% confidence interval estimate of the percentage of adults aged 57 through 85 years who use at least one prescription medication is given as follows;
[tex]CI=\hat{p}\pm z\times \sqrt{\dfrac{\hat{p} \cdot (1-\hat{p})}{n}}[/tex]
Where;
[tex]\hat p[/tex] = 86.6/100= 0.866
n = 3,149
z = The z-value at 90% confidence level = 1.645
Therefore, we get the following confidence interval of the percentage of adults (rounded to one decimal place as required);
[tex]\left (0.866 - 1.645\times \sqrt{\dfrac{0.866 \times (1-0.866)}{3,149}}\right) \times 100 \% \approx 85.6 \%[/tex]
[tex]\left( 0.866 + 1.645\times \sqrt{\dfrac{0.866 \times (1-0.866)}{3,149}} \right) \times 100 \% \approx 87.6 \%[/tex]
The 90% confidence interval, of the percentage C.I. ≈ (85.6%, 87.6%).
